KR0172144B1 - Cylindrical hearing bushing for internal combustion engine - Google Patents

Abstract

FIELD OF THE INVENTION The present invention relates to cylinder liners for combustion power engines, in particular large diesel engines, which cylinder liners have spherical graphite as a base alloy.                 Cast from cast iron, the alloy structure of the cast iron has a cementite / steerite structure that is uniformly distributed in a mesh with clear boundaries.                 As elements boron and / or phosphorus and, if necessary, additionally nickel, molybdenum, chromium, titanium, nitrogen, tin and vanadium are added in the prescribed composition.

Description

            Cylinder Liner for Internal Combustion Engines         

The present invention relates to a cylinder liner for an internal combustion engine, in particular a large diesel engine.

From the European Patent Application No. 0 525 540 A1 specification a cylinder liner is known, in particular for large diesel engines, which cylinder liner is used as a base alloy.                 Cast from cast iron cast iron (nodular graphite cast iron), the structure of cast iron occupies an area fraction of 3 to 8%                 It has a cementite / steatite tissue that is uniformly distributed in a net with clear boundaries. In addition, the base alloy                 0.01 to 0.03 wt% boron and / or 0.2 to 0.4 wt% phosphorus and, if necessary, 0.1 to 0.3 wt% vanadium as alloy elements                 Is added.

Such cylinder liners have very high strength and very good wear and running characteristics. This high strength prevents cracking in modern high power diesel engines.                 Is essential.

It is an object of the present invention to further improve good properties such as heat resistance at high temperatures, molding stability and wear resistance in a cylinder liner of the type described above.

The object is to provide a cylinder liner with a ferrite-based cast iron made of an alloying element according to claim 1 and a spherical graphite having an extreme value thereof according to the present invention.                 By casting. This alloy structure accounts for an area fraction of 3 to 8% and is uniformly distributed in the shape of reticulated cementite / steerite structure.                 Have

The peculiarity of such a structure is obtained by the addition alloy element. That is, spheroidal graphite is formed by adding Mg or Mg and Ce in a known manner,                 Sedimentite / steerite is separated and precipitated instead of graphite tissue in the melt, and the tissue is arranged in a mesh with spatially clear boundaries;                 Matching the area fraction is achieved by adding a small amount of boron and / or phosphorus and, if necessary, vanadium to the ferritic cast iron of the composition:

2.8 to 3.9 weight percent carbon,

Silicon 1.5-3.0 wt%,

Manganese 0.05-1.0 wt%,

Less than 0.02% sulfur;

Magnesium from 0.025 to 0.07% by weight,

0.1 to 2.0 wt% copper

The balance is a base alloy of iron, in particular the proportion of the weight percent of the additive alloy element is as follows:

0.05 to 0.03 wt% boron and if necessary

0.01 to 0.4 wt% phosphorus,

Vanadium 0.05 to 0.4 wt%.

In addition to this, the addition of alloying elements with the following analytical limit values leads to the production of fine stripe-type ferrites, a significant reduction in the ferrite fraction, and the special carbide / nitride                 The production provides better properties such as heat resistance at high temperatures, molding stability, high wear resistance:

0.01 to 2.0 wt% nickel,

Molybdenum 0.1-1.0 wt%,

0.05 to 0.5% by weight of chromium,

0.01-0.05% titanium,

0.002 to 0.014 weight percent of nitrogen,

0.005 to 0.1 weight percent tin.

By spheroidizing graphite, the tensile strength and impact toughness of the cylinder liner alloy structure are enhanced.

With a clear boundary in the alloy structure, the cementite / steerite structure has a specific spatial arrangement, thus allowing the cylinder surface to be reduced as in the corresponding alloy cast iron with layered graphite.                 It will have a fine mesh relief under the microscope, which ensures good adhesion of the lubricant film. Thereby, the piston ring on the cylinder liner                 To ensure good running.

By adjusting the boron, phosphorus and vanadium components to the analytical extremes described above, the desired properties of the cast part can be obtained and optimized to specific properties for specific applications.                 have. For example, phosphorus not only increases abrasion resistance but also brittleness, but is cemented / stearite by three alloying elements of boron, phosphorus or vanadium.                 An optimal reticulated distribution of tissue is provided. Boron not only provides the best wear resistance to the alloy structure, but also somewhat good cementite / steerite like phosphorus.                 While providing a distribution of tissues, vanadium supports tensile elongation and wear resistance but does not act as a net distribution of cementite / steerite tissues.                 Thus, without boron and / or phosphorus, it is of little use as an additional alloying element.

Thus, the cylinder not only meets the prescribed requirements for tensile strength and wear resistance during the casting process, but at the same time has the surface properties necessary for sufficient lubrication                 It is relatively advantageous to plan the liner to be manufactured.

Claims (2)

Spherical graphite and the following analysis limit values: 2.8 to 3.9 wt% carbon, 1.5 to 3.0 wt% silicon, 0.05 to 1.0 wt% manganese, sulfur                 Less than 0.02% by weight, 0.025% to 0.07% magnesium, 0.1% to 2.0% copper, 0.05% to 0.03% boron or 0.1% phosphorus                 To 0.4 wt%, nickel 0.1 to 2.0 wt%, molybdenum 0.1 to 1.0 wt%, chromium 0.05 to 0.5 wt%, titanium 0.01 to                 0.05 wt%, nitrogen 0.002 to 0.014 wt%, tin 0.005 to 0.1 wt%, the balance being made of ironite-based cast iron,                 The cast iron structure accounts for an area fraction of 3 to 8% in the spherical perlite precipitate and is uniformly distributed in a mesh with clear boundaries.                 A cylinder liner for an internal combustion substrate, comprising: Spherical graphite and the following analysis limit values: 2.8 to 3.9 wt% carbon, 1.5 to 3.0 wt% silicon, 0.05 to 1.0 wt% manganese, sulfur                 Less than 0.02% by weight, 0.025% to 0.07% magnesium, 0.1% to 2.0% copper, 0.05% to 0.03% boron or 0.1% phosphorus                 To 0.4 wt%, nickel 0.1 to 2.0 wt%, molybdenum 0.1 to 1.0 wt%, chromium 0.05 to 0.5 wt%, titanium 0.01 to                 0.05% by weight, 0.002% to 0.014% by weight of nitrogen, 0.005% to 0.1% by weight of tin, the balance being made of ferritic cast iron containing iron,                 The cast iron has 0.05 to 0.4% by weight of vanadium with respect to the weight of the balance of iron as an alloying element, the structure of the cast iron is 3 to the spherical pearlite precipitate                 For internal combustion substrates comprising an area fraction of from 8% to 8% and containing cementite / steerite structure parts uniformly distributed in a mesh with clear boundaries                 Cylinder liner.